This invention involves a rotary piston motor having pistons that reciprocate parallel to a central drive shaft while the pistons also rotate around that drive shaft with the engine casing remaining stationary.
Such rotary motors have been previously designed for envisioned use as motors to rotate a shaft, or conversely to pump fluid from the piston cylinders if power is supplied to rotate the shaft. But prior rotary motors have not been commercially viable products, in part because of unacceptable wear, reliability and performance, and in part because of the engine complexity. There is thus a need for a rotary piston motor that is simpler yet more reliable.